Chemistry and Materials Science

Abstract: In metal Binder Jetting Additive Manufacturing (BJAM), the polymeric binder is often treated as a temporary, almost incidental consumable — yet it silently governs nearly every outcome of the process, from droplet ejection to the properties of the final sintered part. This review reframes the binder as a central design variable and examines it through a polymer-science lens, tracing its influence along the complete BJAM process chain. We first dissect binder chemistry and architecture, organizing aqueous, solvent-based, and reactive systems by carrier medium and bonding mechanism, and linking molecular features — functional groups, chain entanglement, and crosslinking — to printability, green strength, and clean thermal removal. We then follow the binder into the powder bed, where rheology, droplet dynamics, and capillary migration dictate spreading, penetration, and shape fidelity; into the green part, where adhesion and particle bridging set mechanical integrity; and through debinding and sintering, where decomposition chemistry, residual carbon, and densification determine final quality. A survey of automotive, energy, aerospace, biomedical, and tooling applications highlights where binder limitations still constrain industrial adoption. Throughout, we emphasize the recurring trade-offs — jettability versus green strength, penetration versus saturation, and burnout cleanliness versus chemical composition — that any next-generation binder must resolve, and we outline design criteria toward predictive, application-specific binder development.

Abstract: Alloying titanium with small amounts of copper not only increases its strength and corrosion resistance but also imparts antibacterial properties, which are beneficial for implant transplant operations. In this study, two binary Ti–Cu alloys containing 5 and 10 weight percent Cu were produced using an arc-melting process under a controlled inert atmosphere. The cast ingots were annealed at 900 and 1050 ℃ for 2h, followed by furnace cooling. Characterization using XRD and SEM-EDX techniques revealed a pronounced presence of the α-Ti(Cu) phase, which formed below the eutectoid point, along with the hypereutectoid intermetallic phases. Phase analysis, microstructural characterization, and electrochemical testing showed that increasing the Cu content and annealing temperature in Ti–Cu alloys increased the amount and size of the intermetallic phase(s), resulting in significantly improved corrosion performance. This study demonstrates correlation between phase, morphology and corrosion resistance in binary Ti–Cu alloys.

Abstract: This study employs ab initio density functional calculations, combined with site projected density of states, spatial charge redistribution maps, and thermodynamic and kinetic analyses, to investigate how externally applied positive charges alter the interfacial adsorption behavior of Y, Y₂O₃, and Y₂O₂S on C(001) and C(100) crystal surfaces. The analysis results reveal that C(001) and C(100) form opposite response states under the condition of externally applied positive charges. On the C(001) surface, the increase of positive charges interferes with the charge transfer between the O-2p orbitals and Y-4d orbitals in the inclusions and graphite, thereby weakening the adsorption of inclusions on the graphite surface. Compared to the Gibbs free energy value without positive charges, it is larger, indicating a significant decrease in spontaneous deposition and reactivity tendency. The increase of positive charges leads to a lower steady-state adsorption capacity of C(001) and a gradual decrease in both the inclusion adsorption rate constant and the adsorption capacity. The dangling bonds and defect states on the C(100) surface provide additional quantum channels for charge transfer. External positive charges may promote the rehybridization of dangling bonds on the C(100) surface, which in turn reduces the energy difference between Y-4d and O-2p (or surface C-2p) orbitals, promotes orbital overlap, and strengthens the electronic coupling at the interface. The opposite responses of C(001) and C(100) to positive charges are essentially manifestations of anisotropic behavior between graphite basal planes (dominated by uniform electron distribution and electrostatic repulsion) and edge planes (dominated by abundant dangling bonds, local polarization, and orbital coupling).This discovery holds significant guiding importance for electrochemical anti-blocking technology: the inhibitory effect of impressed current on inclusion adsorption exhibits crystal face selectivity, being effective only on inert basal planes like C(001), while it may have the opposite effect on highly active edge/defect faces.

Abstract: Downhole tubulars in high-sour gas fields operate under extremely harsh conditions rarely seen in other industrial scenarios. With H2S partial pressures exceeding 1 MPa, Cl- concentrations reaching 2×105 mg·L-1 and frequent elemental sulfur deposition, the synergistic action of these corrosive species drives corrosion rates and cracking susceptibilities far beyond predictions from conventional single-medium tests. Based on field experience from China’s major high-sour gas blocks and extensive published literature, this review maps the operating window onto a three-dimensional service-boundary space defined by H2S partial pressure, temperature and Cl- concentration, and illustrates how temperature-dependent reaction pathways of elemental sulfur significantly shrink the valid service window of tubular materials. It clarifies the chained-evolution law among mass-loss, localized-defect and environment-assisted cracking failures, revealing that abrupt tubular failures typically occur after material service boundaries are exceeded. Five typical tubular material systems are compared regarding cost, mechanical performance and corrosion resistance. Advances in corrosion inhibitors, surface coatings and localized monitoring are reviewed, a closed-loop integrity-management framework for life-extension decision-making is proposed, and key technical bottlenecks for super-deep wells and emerging scenarios including CCUS, geothermal exploitation and underground hydrogen storage are highlighted.

Abstract: The development of steels with good mechanical properties is crucial for high-strength and deflection fabrications. This paper investigates the effect of annealing temperature on a microstructure, texture, and dynamic mechanical behavior of an AISI 321 metastable austenitic stainless steel (MASS) initially subjected to rotary swaging. Gradient distribution of α’-martensite, austenite grains with γ-fiber, B/-B and Rotation-Cube orientations, as well as BCC/BCT grains with α-fiber, D₁/D₂, and F orientations is detected in the radial direction of an as-swaged bar. The program steel after post-swaging annealing in the low-temperature range (550-650°C) exhibits increased Charpy V-notch impact toughness due to an increase in crack propagation energy. The toughening is associated with formation of microvoids within wide microzones with the γ-fiber orientation and along phase boundaries, which are elongated in the axial direction of the bar. Therefore, crack deflection along these lines occurs. In fact, the trade-off between dynamic strength and Charpy impact toughness of the AISI 321 steel is overcome. The effect of post-swaging annealing conditions on the microstructure/texture evolution, crack nucleation energy, crack propagation energy, dynamic strength, and fracture mechanisms is revealed and discussed. Thus, a strategy of simultaneous strengthening and toughening of MASSs is proposed.

Abstract: Oxidation embrittlement at operating temperatures is a major concern in TiAl4822 that are widely used in jet engine blades. Previous studies on oxidation embrittlement of TiAl alloys, including TiAl4822, have focused primarily on tensile properties under specific oxidation conditions. In this study, we examined embrittlement behavior from the perspective of impact resistance that more closely reflects real-world requirements using samples oxidized at various temperatures and for different durations. Even mild oxidation (e.g., 10 min at 500 °C) caused embrittlement at 25 °C. However, the change in the degree of embrittlement under more severe oxidation conditions (e.g., 1h at 900 °C or 1,000 h at 700 °C) was not significant. Conversely, extreme embrittlement occurred at 1100 °C and above. This was attributed to the influence of an altered layer containing cracks that was formed at the interface between the base metal and the oxide layer. No embrittlement occurred at a test temperature of 200 °C. Preventing moisture adhesion on the oxidized surface reduced embrittlement. These results suggest that environmental embrittlement due to the preferential adsorption of moisture on oxidized surfaces may be an additional embrittlement factor, alongside previously recognized factors such as oxygen penetration.

Abstract: The influence of quenching media on the residual stress of 7136 aluminum alloy extrusions was studied by finite element simulation method. The results show a compressive stress at the component surface and a tensile stress at the center. The maximum compressive and tensile stress are 67.2MPa and 82.6MPa when quenching with 20℃ water. Increasing the water temperature to 80℃ can lead to the decrease of the maximum residual stress by 31.5% and 26.3%, respectively. When quenching in the PAG solution, the residual stress will decrease with the increased concentration. For example, the maximum compressive and tensile stress will drop by 26.4% and 34.7% in 10% PAG solution compared with 0% solution (20℃ water). On the other hand, the increase of NaCl quenching solution will lead to a rise in the residual stress. When adding 20% NaCl from 0%, the compressive and tensile stress can increase by about 21.2% and 5.6%. It can be known from the results that the cooling rate of the alloy component under different quenching conditions will change, which causes the difference in the residual stress. It will be an effective method to control the residual stress through appropriate adjustment of quenching medium parameters.

Abstract: To strengthen and toughen welded joints of marine steel, this study first optimized the welding process parameters. Subsequently the Fe-Mn-Si shape memory alloy (SMA) welding seam with stress-adaptive characteristics was fabricated based on phase transformation strengthening method. Then the mechanical properties of test materials were compared with those of conventional marine steel welded joints with YJ501-1 welding seam, and the former strengthening and toughening mechanism was investigated finally. The results demonstrate that under the optimal process parameters (welding current of 140 A, an arc voltage of 30 V, and a welding speed of 3 mm/s), the prepared Fe-18Mn-4Si-11Cr-6Ni SMA welding seam can effectively reduce the residual stress of the welded joint, while significantly improving its tensile strength, impact toughness and hardness. XRD characterization further reveals that the underlying strengthening mechanism is attributed to the residual stress induced γ↔ε martensitic transformation in the Fe-Mn-Si SMA welding seam.

Abstract: Single crystals of different V(Sn,Sb)₂ phases were grown via self-flux method by employing excess of Sn and Sb. The obtained crystals were studied using X-ray diffraction and EDX spectroscopy, which revealed the existence of two new ternary phases and two solid solutions based on the binary VSn₂ to VSb₂ phases showing peculiar multi-step structural evolution upon going from the VSn₂ side to the VSb₂ side of the system. The first novel phase τ₁ crystallizes in the monoclinic unit cell, while the second phase – τ₂ – adopts orthorhombic crystal structure. The discovered phases derive their structure from the parent phases VSn₂ and VSb₂ and are built from linear chains of fused V(Sn,Sb)₈ antiprisms. These chains are then coupled into layers, which are stacked either right on top of each other or with a with 60° twist. The twists are supported by Sn atoms located at a boundary between the layers. Thus, upon going from VSn₂ to VSb₂, the number of twists per layer decreases from 1 in VSn₂ to 2/3 in τ₁, and to 1/2 in τ₂, ultimately ending at 0 in VSb₂. While the Sn atoms have larger radius compared to that of Sb, the volume per one atom decreases in the VSn_x’Sb_2-x’ solid solution with the increasing Sn content before returning to the expected increase in the τ₁-τ₂-VSn_2-xSb_x sequence. The decrease in volume in the former is caused by the decrease in V-V distances inside the chains, which is caused by the change in character of the V-E interactions, where Sb atoms form two-center V-Sb bonds, while Sn atoms act as bridges forming three-center V-Sn-V bonds as revealed by our DFT-calculations.

Abstract: Al-Zn-Mg-Cu-Zr alloys are widely utilized in aerospace applications; however, their strength typically remains below 800 MPa, insufficient for growing industrial demands. This research therefore aims to enhance their mechanical properties by investigating the effects of heat treatment on both performance and microstructure. The research utilized experimental investigations to resolve the problem. To prepare 800 MPa-grade Al-Zn-Mg-Cu-Zr alloys, the effects of different heat-treatment methods on the microstructure and properties of the alloys were investigated. The results show that the hardness during single-stage aging exhibits a double peak characteristic, and the peak aging time of the Al-Zn-Mg-Cu-Zr alloy was 18 h. The alloy grain size follows the order: peak aging < over-aging < double aging < retrogression and re-aging (RRA). The grain boundary precipitates gradually evolved from a continuous network in the peak-aged condition to a coarsened and discontinuous distribution. The tensile strength of the alloy was ranked as follows: peak aging > RRA > over aging > double aging, whereas the elongation followed the order: RRA > peak aging > double aging > over aging. The RRA aging treatment provided the greatest improvement in the overall properties of the Al-Zn-Mg-Cu-Zr alloy, whereas the peak aging treatment yielded the highest tensile strength.

Abstract: Aged pipeline networks are exposed to interacting operational, electrochemical, structural, and metallurgical degradation mechanisms that are commonly assessed independently, limiting the diagnosis of system-wide failure propagation. This study develops an integrated and interpretable fuzzy-logic framework for detecting, quantifying, and isolating failure scenarios in a 572 km pipeline transportation network. The methodology combines approximately 2.5 million historical SCADA and SAP records, cathodic-protection and soil measurements from 89 evaluation points, 5661 ultrasonic-inspection anomalies, mechanical and metallographic characterization of API L X65 steel, and validated expert knowledge. Four Mamdani fuzzy inference systems were constructed to represent operational capacity, cathodic-protection performance, mechanical integrity, and metallurgical degradation. Their outputs were integrated into a unified fault-signature matrix comprising 28 failure scenarios. Scenario FS-3 produced the broadest systemic response by activating all diagnostic residuals, whereas metallurgical scenarios FS-22 – FS-28 activated 61% of the matrix, indicating their extensive influence on pipeline integrity. Structural scenarios FS-15 – FS-21 exhibited progressively broader signatures as wall deterioration increased, while FS-1, FS-2, FS-5, FS-6, and FS-7 remained localized and were more readily isolated. The proposed framework preserves diagnostic traceability through explicit input variables, fuzzy rules, and residual signatures, providing an interpretable basis for failure classification, Diagnostic signature breadth, maintenance prioritization, and operator decision support. Its conclusions are limited to the analyzed network and require external validation before application to other pipeline systems.

Abstract: Predicting yield strength (YS), ultimate tensile strength (UTS), and elongation (El) in heat-treatable aluminum alloys is challenging because of nonlinear interactions between alloy composition and heat-treatment parameters. This study proposes a physics-retained, explainable, and uncertainty-aware multi-target machine-learning framework for simultaneous strength–ductility prediction. A hybrid feature-selection strategy combining statistical relevance, mean embedded importance, and metallurgical retention reduced the input space from 17 to 12 variables while preserving solution treatment temperature, aging temperature, and aging time. A matched 17-feature comparator was evaluated using the same repeated outer-validation splits, inner tuning procedure, model families, hyperparameter-search space, and search budget. Across 25 outer evaluations, the 12-feature pipeline achieved a macro-averaged R2 of 0.807 ± 0.043, macro-NRMSE of 0.424±0.047, and macro-NMAE of 0.293 ± 0.033, compared with 0.800 ± 0.047, 0.431 ± 0.052, and 0.294 ± 0.040, respectively, for the 17-feature pipeline. An exploratory post-selection paired comparison yielded a mean macro-R2 difference of 0.0068, a corrected 95% interval of [−0.0198,0.0335], and p = 0.602. Because k = 12 was selected using the same outer-validation summaries, these statistics are descriptive rather than confirmatory. The selected pipeline therefore used 29.4% fewer descriptors with similar observed mean performance, although superiority or statistical equivalence was not established. On the untouched final-test partition, the locked 12-feature ExtraTrees model achieved target-wise R2 values of 0.857, 0.842, and 0.826 for YS, UTS, and El, respectively. SHAP assigned the largest model attributions to Zn, Cu, and selected heat-treatment conditions; these attributions explain model behavior rather than causal metallurgical effects. Ensemble-conformal intervals supported uncertainty-aware retrospective prioritization of held-out conditions. However, because no external or experimental validation was performed and performance decreased under composition-group-disjoint validation, the framework should be regarded as an internally evaluated modeling workflow rather than a validated alloy-design tool.

Abstract: Beryllium-tungsten (Be-W) intermetallic compounds with low density, high elastic modulus, high melting point, and outstanding irradiation and corrosion resistance are promising candidates for extreme-environment applications, including fusion reactor plasma-facing components, aerospace high-temperature structures, and nuclear reactor functional materials. Herein, first-principles calculations based on the density functional theory (DFT) plane-wave pseudopotential method were performed to systematically explore the crystal structure, thermodynamic stability, electronic structure, bonding characteristics, and mechanical properties of three typical Be-W intermetallics (Be2W, Be12W, and Be22W). The consistency between optimized lattice parameters and experimental data validates the accuracy of the computational model. The calculated results reveal that Be12W has the lowest formation enthalpy and superior phase-forming capability, whereas Be2W presents the highest cohesive energy and Fermi level density of states, corresponding to inferior thermodynamic stability. All three intermetallics are mechanically stable and intrinsically metallic, with chemical bonding primarily governed by strong Be-p–W-d orbital hybridization and distinct covalent features. Mechanically, Be2W exhibits excellent volumetric deformation resistance, Be12W achieves the highest shear and Young’s moduli with optimal comprehensive mechanical performance, and Be22W possesses relatively poor mechanical properties. This work elucidates the inherent correlations between the structural, electronic, thermodynamic, and mechanical behaviors of the Be-W system, offering reliable theoretical guidance for the composition optimization, phase control, and fabrication design of advanced B-W based high-temperature irradiation-resistant structural materials.

Abstract: Al-NiO thermites are recognized for their high energy density, low gas emission, and stable at normal conditions, making them ideal for applications requiring high concentrated heat. This study investigates the influence of three physical mixing techniques—mortar-pestle, magnetic stirring, and ball milling—on the morphology, reactivity, and thermal behaviour of Al-NiO thermites under different heating rates (20, 35, 50 oC/min). Advanced characterization techniques, including SEM/EDS, particle size distribution (PSD) analysis, zeta potential (ZP), DSC/TGA, and electrothermal ignition tests, were employed. The results reveal that ball milling significantly reduces particle size to the nanoscale and enhances ignition properties, despite limited improvements in homogeneity due to agglomeration tendencies. Thermal analyses showed that, while all techniques produced good thermal properties, the ball-milled thermite demonstrated activation energy and ignition characteristics consistent with nanoscale systems. Faster heating rates revealed distinct morphological outcomes and reaction pathways among mixing techniques. Importantly, this study demonstrates that cost-effective mixing methods can still yield thermites with promising thermal and ignition properties, suggesting their potential for scalable industrial applications. These findings contribute to optimizing Al-NiO thermites for advanced energetic systems in both civilian and military domains.

Abstract: Point to the manufacturing process of variable-section rectangular tube, a four-die radial extrusion process was designed in this article. The general deformation law was researched in two-dimensions, the influence of deformation parameters on the deformation results was explored, and the method by using the mold anti-deformation to eliminate the concave defects was proposed. For the tube parts with common thickness to diameter ratio, the corresponding optimal die arc degree is obtained through simulation and optimization. After that, the two-dimensional deformation law is applied to three dimensions, and the methods to eliminate the defect are carefully studied and successfully realized. Taking a variable-section rectangular tube as an example, the experiment was carried out. The experimental results were compared with the simulation results, and the accuracy of the simulation results and the feasibility of the process were verified.

Abstract: Dephosphorisation in oxygen steelmaking depends on more than the equilibrium phosphorus partition ratio. It also depends on where gas, slag, metal and injected lime powder coexist while the bath is being stirred. We develop a gas–slag–metal–particle reaction model for bottom-blown oxygen–CaO powder injection by coupling Euler–Euler transport of liquid steel, mixed slag and gas with discrete CaO-particle motion. The local source terms include oxygen dissolution, FeO/Fe₂O₃ conversion, CO/CO₂ buffering, competitive C/Si/P oxidation, P₂O₅ formation, C₂S–C₃P fixation, reaction heat and phase-wise mass conservation. Instead of resolving every bubble or slag droplet, the model represents bubble swarms, dispersed slag and emulsified metal–slag contact through mean-field interfacial area densities tied to local phase fractions and mixing. Two cases with the same initial phosphorus content but different carbon levels are used to test reaction selectivity. In the high-carbon bath, bottom-blown oxygen is consumed first by decarburisation; the generated CO sustains plume buoyancy but reduces FeO_x retention during flotation. CaO addition improves local slag formation, but it contributes to dephosphorisation only where FeO_x supply, P₂O₅ generation and C₂S–C₃P fixation coincide at an active slag–metal interface. The stable dephosphorisation window therefore lies mainly in the upper slag–metal mixing zone, not in the bottom gas column. The model provides a computable basis for analysing bottom powder injection, combined blowing and low-carbon endpoint dephosphorisation in gas–slag–metal reactive flows.

Abstract: Cu-based interpenetrating phase composites (IPCs) represent a paradigm for sliding electrical contacts where the synergy between thermal management, wear resistance, and electrical transport is critical. Herein, we engineer Cu-(CrWₓ)C IPCs (x = 0, 10, 25, 50 wt%) via pressureless infiltration, elucidating a tungsten-mediated architectural stabilization mechanism. We demonstrate that controlled W incorporation refines the carbide skeleton, optimizing the load-transfer efficiency between the rigid ceramic network and the continuous Cu-rich functional phase. Microstructural characterization (XRD, SEM/EDS) confirms the intact three-dimensional interpenetration, with higher W content promoting the segregation of W-rich domains. Quasi-static compression (10-3 s-1) validates the structural robustness under large-strain regimes. Notably, all composites retain high electrical conductivities (~39–41 % IACS); the Cu-(CrW10)C variant exhibits the peak thermal conductivity at 500 °C. Tribological evaluations reveal that optimal wear resistance is decoupled from peak hardness; instead, it arises from the stabilization of a skeleton-supported tribo-damaged layer facilitated by moderate W addition. Conversely, excessive W enrichment induces brittle fragmentation and interfacial debonding, exacerbating third-body abrasion. Quantitative analysis using a Thermo-Tribological Performance Index (TTPI) and an Electrical-Thermal-Wear Balance Index (ETWBI) confirms that Cu-(CrW10)C achieves the optimal equilibrium among material removal resistance, heat dissipation, and dimensional stability. This work establishes a design strategy for high-performance IPCs by leveraging architectural tuning to reconcile traditionally conflicting property requirements.

Abstract: Sintering diagram for copper fibers is established based on a two joint-fiber geometric model and intrinsic material constants, with comprehensive consideration of four neck-growth mechanisms: volume diffusion, grain-boundary diffusion, surface diffusion and Nabarro-Herring microcreep. The sintering diagram reveals that grain-boundary diffusion dominates neck growth at relatively low temperatures, surface diffusion prevails at high temperatures for short holding time, and Nabarro-Herring microcreep acts as the primary mechanism at high temperatures for long holding time, respectively. In addition, synchrotron radiation X-ray computed tomography (SR-CT) characterization is adopted to validate the established sintering diagram via the measured neck size of sintered fiber joints. The experimental results show that most measured neck-size data points lie close to the theoretical curve predicted by the Nabarro-Herring microcreep mechanism when sintered at 1030 oC for 30 min, 60 min and 180 min. This result confirms that Nabarro-Herring microcreep is the predominant neck-growth mechanism at high temperatures for long holding time, which is consistent with the theoretical result derived from the sintering diagram. Meanwhile, the results also prove the existence of Nabarro-Herring microcreep during the high-temperature sintering of copper fibers without externally applied pressure.

Abstract: This article analyzes in detail the structural, thermal and mechanical properties of the Ni₅₄Cr₂₈Mo₈Nb₅Ta₅ alloy, as well identify potential applications in areas where exceptional high-temperature performance is required — such as gas turbines, nuclear reactors or aeronautical engine components. Obtaining a very good correlation between the experimental and fitted profiles, as well as the low values of the error parameters (R-factors), confirms the accuracy of the structural model and the validity of the phases identified following the XRD analysis. The study also aims to highlight the relationship between chemical composition, microstructure and mechanical behavior, providing a basis for optimizing heat treatments and manufacturing processes of this advanced superalloy.

Abstract: Platinum-Rhodium alloys are one of the prominent alloys used in the high temperature and high corrosion environment. Due to the nature of Pt and Rh, it maintains the single solid solution phase up to very high temperature. In order to develop and design a new part to be used in the field, many techniques, tools, software in combination are needed. Phase field method (PF) is used for microstructure prediction or finite element method (FEM) for stress analysis. Those methods require additional data such as thermodynamic stability for PF and elastic modulus for FEM. Pt-Rh binary system, the experimental data for thermodynamic stability and elastic properties are very limited and mostly available only for pure elements. In this work, we performed first-principles calculations to predict the temperature dependent elastic properties of fcc-disordered PtRh alloys at various concentrations. The special quasirandom structures (SQS) are used to describe the disordered structure of fcc-disordered PtRh alloys. Vibrational contribution to the free energy are performed with the quasi-harmonic phonon approximation to obtain the finite-temperature free energy and coefficient of thermal expansion for the fcc-disordered PtRh alloys. The elastic stiffness of the fcc-disordered PtRh alloys at different concentrations are obtained through the energy-strain method. By coupling between calculated coefficient of thermal expansion and the elastic stiffness data calculated at various volumes, the finite-temperature elastic stiffness of the fcc-disordered PtRh alloys can be obtained.